Service providers (SPs) are increasingly using Multi-protocol Label Switching (MPLS)/Internet Protocol (IP) networks for delivering various types of services. In SP networks consisting of an MPLS/IP core attached to one or more Ethernet Access Domains, with pseudowires (PWs) utilized for transporting data traffic over the core, occurrence of faults within the core may cause end-to-end service disruption. (A PW is a tunnel established between two provider edge nodes to transport Layer 2 packet data units (PDUs) across a packet switched network (PSN).) Thus, as more legacy networks migrate to the use of MPLS for transport, the role of MPLS Operations, Administration, and Maintenance (OAM) network fault, performance, data, and diagnosis functions, has become increasingly important.
A number of different OAM mechanisms have been developed for fault detection and isolation in MPLS networks. For example, Virtual Circuit Connectivity Verification (VCCV) is a known mechanism for identifying OAM packets at the egress of a PW. VCCV is thus useful in detecting failures in the forwarding plane on the egress of the MPLS PW. Label Distribution Protocol (LDP) status messages and the MPLS Label Switched Path (LSP) Ping tool provide the capability for detecting and isolating failures in the data plane, and for verifying the data plane against the MPLS control plane. Various Ethernet service OAM mechanisms, such as the Ethernet IEEE 802.1ag Connectivity Fault Management (CFM), Link Layer OAM (IEEE 802.3ah OAM), and Ethernet Local Management Interface (E-LMI) (Metro Ethernet Forum Technical Specification 16), also enable a user to detect faults within Ethernet domains.